It’s going to be an interesting summer for Dropbox and Box in light of Amazon Web Services’s new Zocalo enterprise document sharing and collaboration tool. If the phrase “enterprise document sharing and collaboration” sounds familiar, it’s probably because you’ve been reading about how both Dropbox and Box have launched these types of offerings in recent months as a way to distinguish themselves in a crowded file-share-and-sync market.

With Zocalo, Amazon is essentially adding the capabilities of Dropbox and Box to its own platform as it attempts to dominate enterprise IT.

As analyst Janakiram MSV described in a blog posting on Gigaom Research, Zocolo will allow users to edit their documents in the cloud sans Microsoft Office, and any comments or edits made in the cloud can be translated over to a Microsoft Word document if the person happens to use Word to open the same file on his computer. Sound familiar? Dropbox’s Project Harmony, launched in April, essentially does a similar task.

From Gigaom Research:

Zocalo is an enterprise-grade sync service that competes with Dropbox for Business and Box. By providing audit trails with Active Directory integration and role-based security, Amazon’s Zocalo is an assault on Box, which is dreaming of becoming the primary choice of enterprise cloud storage. Box just received $150 million in funding from TPG Growth & Coatue Management. So close to its IPO, Box has a new competitor to contend with.

Matt Wood, general manager of data science at AWS, soft-pedaled the competitive angle on Zocalo as he said “There is a huge opportunity for multiple companies to be successful, especially those trying to reinvent core enterprise solutions… we’re excited to provide infrastructure underneath for partners refining this space.”

For people who’ve been around the block a few times, AWS continues to look more and more like the Microsoft of twenty or so years ago when that company pitched Windows as the platform for an array of partners but kept adding more and more higher-level applications of its own to the mix. Those applications inevitably competed with partner offerings and buried many of them. Witness WordPerfect, Lotus 1-2-3, etc.

“It’s an incredibly exciting time for the cloud content category, and Amazon’s entry underscores the scale of the market opportunity. Amazon Zocalo looks like a useful service for file storage and sharing. At Box, we’re laser focused on offering the security, scalability, collaboration and cross-platform support that enterprises require to be more productive and competitive across workforces of hundreds of thousands of employees.”

It’s hard not to read an “Uh oh” in Levie’s statement regarding Amazon stepping on its turf. It’s pretty typical that when a colossal competitor comes up with a service that is an obvious attempt to capture the market, the smaller incumbent companies claim that this only “validates their strategy.”

Asked for comment, a Dropbox spokesperson said the company “doesn’t have anything to share at the moment beyond what’s public.”